To: GHDL discuss list <>
Subject: [Ghdl-discuss] Re :  Comparison of ghdl and Cadence Incisive

> Good question.
> I'm pretty sure incisive support of VHDL is almost complete, but I have never 
> used it.

We use GHDL as our golden simulator, and then Cadence for synthesis to ASIC, 
but have not extensively used Incisive...

> You can try to run the VHDL test suite but I fear you will spend time to 
> setup it for incisive and the results will be difficult to analyze or even 
> not interesting at all.
> Do you want to know missing features from VHDL or from incisive?

If Incisive uses the same language parser as their synthesis tools (a big if), 
then we have found that it can be brittle.  What tends to break are things that 
you normally don’t find in IP blocks that use ‘simple’ language constructs.  A 
few examples are Multidimensional arrays (what do these represent?  Think 
multiple banks of register files on a DSP for e.g. X and Y, or multiple FIFO 
lanes in a communication core) or VHDL ‘configurations’ (think an entity for 
sim, FPGA and ones to specialize per ASIC process selected with 
‘configuration').  It just can’t handle these sorts of things at all, and you 
have to work around it (in this case, explicitly separate arrays for each lane, 
and only passing the entity of the configuration you want it to use).

To be clear, if your RTL is ‘simple', you will have no problems with the 
proprietary tools… and most is.  Also, they do sometimes fix things like the 
above in their tools.  But it’s also important to understand that it has not 
been the case for a very very long time that GHDL is in error, when the 
proprietary tool (Cadence, Xilinx…) has a mismatch (at least in our 
experience).  It is always because the vendor tool doesn’t implement some 
aspect of the LRM (correctly).


> Tristan.
> ----- Simon Thijs de Feber <> a écrit :
>> I'll need to do a functional comparison between GHDL and Cadence Incisive.
>> I just can throw a IP and it's TB at it to do some checks. However this is
>> not really an intelligent way to do it.
>> How could I approach this ?
>> Take the test suite of GHDL and run this in both simulators ?
>> best regards
>> Simon

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